Steamboat Springs – Rising global temperatures are likely to hasten Colorado’s spring snowmelt and bring hotter, drier summers that will strain water supplies, a climate-change expert told a gathering of water managers on Wednesday.

Human-induced global warming, which could raise average temperatures by 5 degrees or more over the next century, already appears to be speeding up the cycle of evaporation and precipitation, said Joel Smith, one of the authors of the most recent report of the respected Intergovernmental Panel on Climate Change.

Global-climate models also suggest increased occurrences of droughts throughout the West, Smith told the members of the Colorado Water Congress at their annual summer meeting.

“This, of course, could be very serious for water supply,” he said. “We’ll see higher temperatures, drier summers and more demand.”

The issue is critical in Western states such as Colorado, where even in wet years almost every river already is “over-appropriated,” with insufficient water to satisfy demand. Yet population continues to surge.

“We’re pretty sure that what is available now may not be available in the future,” said Frank Kugel of the Upper Gunnison River Water Conservation District.

The three-day conference – which has attracted water suppliers, government officials, scientists and consultants – focuses on water management amid the uncertainties of climate change.

“One question is: Do you plan for the average, or do you plan for the unacceptable?” said Randy Udall, director of the Aspen-based Community Office for Resource Efficiency. “The consensus was you plan for the unacceptable.”

Many water providers, including those in Denver and Colorado Springs, have begun planning for reduced stream flows and reservoir levels, trying to balance the risks and costs in an unpredictable world.

Overall, the region is likely to see wetter winters and drier summers, Smith said, although scientists concede that computer modeling is inexact and there could be great variations from the trends.

But in general, the annual snowpack in the mountains is expected to decrease, and, coupled with an earlier spring runoff, it will affect both the amount of water and when it is available.

“As you’re trying to capture that earlier snowmelt, you may be confronted with flood-control issues,” said Bob Rauscher, Smith’s partner at Boulder- based Stratus Consulting. “You may be having more dam releases early in the season, when you’d rather be capturing it to prepare for that longer, hotter summer.”

Water quality also likely will be affected: Warmer temperatures tend to induce algae blooms in reservoirs and contribute to the size and severity of forest fires – a major source of sedimentation – and salinity is expected to rise with increased evaporation.

Eastbound lanes of Interstate 70 were closed Saturday afternoon at Georgetown due to a semitrailer fire, the Colorado Department of Transportation tweeted. The right lane remains closed, while the other lanes have since reopened. Drivers can expect heavy delays, transportation officials said. The fire initially closed both sides of the interstate as smoked crossed the highway. The load on the...